How can you determine whether a composite monofilament is delaminated or damaged?

To determine whether a composite monofilament has delamination or structural damage, a comprehensive inspection is required, combining visual assessment, tactile examination, and actual performance under use. The following are several practical and reliable methods:

1. Visually inspect the surface condition.

• Observe whether the wire harness exhibits localized bubbling, bulging, color differences, whitening, or delamination of the outer layer.

• When viewed under strong light or with a magnifying glass, if you notice gaps, cracks, or inconsistencies in transparency between the outer material and the inner core, it could indicate adhesive failure or the onset of delamination.

2. Bending and Handfeel Testing

• Gently bend the curved segment with your fingers:

  • A normally compounded monofilament should be flexible and evenly stressed.

  • If a certain area feels unusually stiff, makes a “click” sound, or cracks on the outer layer when bent, exposing an inner core of a different color, it indicates that the structure has been damaged.

• Lightly scratch the surface with your fingernail: If the outer layer easily scrapes off or peels away, it indicates poor adhesion between layers.

3. Knotting Test (Handle with Care)

• Cut a short length of line and tie a standard knot (such as the improved Clinch knot). Then, slowly tighten it:

  • A healthy composite monofilament should bear stress uniformly and remain tightly knotted without slipping.

  • If the outer layer slips during knotting, the inner core shrinks, or there is obvious delamination or fracture near the knot resembling a “sleeve-like” structure, it indicates that the composite structure has failed.

4. Fracture analysis (if the wire has been broken)

• Examine the fracture morphology:

  • Normal fractures are typically neat or fibrous and streaked.

  • If the fracture surface exhibits either **“an intact outer layer with the inner core pulled out”** or **“separation between the inner and outer layers, with misalignment at the fracture section,”** it can generally be determined that the loss of strength is caused by delamination.

5. Abnormal phenomena during use

• The line suddenly broke during casting, but there was no obvious snagging on the bottom or damage to the fish’s teeth.

• The wire exhibits abnormal wear at the guide ring, with localized areas rapidly becoming thinner or fuzzy.

• Breaking suddenly under slight stress after prolonged disuse—these could all be signs of aging in the internal structure.

6. Environmental and Usage Time Reference

Composite monofilaments are more likely to delaminate if exposed for extended periods to the following environments:

• Strong ultraviolet radiation exposure (such as outdoor storage during summer);

• High temperature and high humidity (such as prolonged exposure to sunlight in a car or in tropical waters);

• Contact with oils, solvents, or strong oxidizers.
  Even if the appearance is intact, it’s recommended to replace it after more than one year of use—especially if you frequently go sea fishing.